What makes you assert that Audirvana is "in the Roon League"? As a 4+ year Audirvana user (on Mac) IMHE, Audirvana pales in comparison to Roon.
While I'd also enjoy reading of ISO files, it seems like low demand will keep that enhancement as a backlog item for most developers. I would guess that other user requested enhancements will keep this a low priority for some time unless demand increases. Cheers,
Spencer